Reading a pocket barometer on hut-to-hut walks

Between two huts the forecast you read at breakfast is already old. A pocket barometer gives you a second opinion every hour, if you know what the needle is telling you. ZEPHYR-BODY-ORGANIC

What a fall means

At a fixed altitude, a drop of three hectopascals or more in three hours usually means weather is coming within half a day. Overnight in a hut the altitude does not change, so the reading is clean: note it at dinner and again at first light.

On the move it is harder. Climbing three hundred meters lowers the reading by about thirty-five hectopascals, which swamps any change in the weather. Read it at stops, at known heights, and compare like with like.

A rule for the morning

If the needle fell more than four hectopascals overnight, take the lower route and be across the pass by noon. If it held steady or rose, the ridge is usually fine. Either way, the sky has the last word.

Further reading: a longer note on altimeters, a table of pressure changes, hut opening dates.